A new report reveals that President Donald Trump’s national security adviser, H.R. McMaster, has grown “increasingly volatile” in the White House but that John Kelly, his chief of staff, has assured him his job is safe.

The negative stories surrounding his time in the White House are causing McMaster to lose his cool, according to a Politico report citing White House officials who have interacted with the general.

“McMaster, whose temper is legendary, frequently blows his top in high-level meetings,” the report notes, citing national security leaks that he believes undercut his authority. McMaster and Steve Bannon also clashed with each other in front of the president during a reported meeting about a strategy on Afghanistan.

Reports Thursday revealed that McMaster concluded that former National Security Adviser Susan Rice did nothing wrong, amidst questions about her decisions to unmask the identities of Trump transition officials communicating with Russians. A letter from McMaster to Rice also surfaced, showing that he assured her that her security clearance would remain intact.